The present invention relates to a simplified supplying system of the position identification potentiometer of electronic memory mechanisms of a motor for setting an adjusted position of automobile vehicle seats and the like.
At present, each seat setting electronic memory mechanism is connected by an array of five lines to an electronic module which is internal or external to the seat.
Actually, two lines are respectively connected to the terminals of the mechanism setting motor in consideration so as to supply the motor with the battery voltage, two other lines are moreover respectively connected to the identification potentiometer terminals so as to supply this potentiometer with a voltage which is in general a regulated voltage of about 5 volts, whilst a fifth line connects the potentiometer slider to the electronic module, the signal corresponding to the position of the slider determining the setting position.
The present invention aims at omitting the connection of the two potentiometer supplying lines with the electronic module by connecting directly these two lines in parallel with the setting motor.
With such an assembly, it is unnecessary to provide a distinct supply for the potentiometer which is supplied only if the motor is itself energized.
However, since the polarity of the voltage applied to the motor has to be switched according to the rotation direction imposed to the motor, the potentiometer slider, supplied with the same voltage as the motor, does not apply to the electronics the same indication each time for a given position of the slider.
Thus and by way of example, let us consider a power supply of 12 volts and the slider on the 3/4 of its maximum stroke (as shown in the accompanying drawing). For a given rotation direction of the motor, the signal issued from the slider will be of 3/4.times.12 volts=9 volts with respect to ground, but it will be of only 12-9 volts=3 volts for the same position of the slider when the polarity will be reversed in order to rotate the motor in a reverse direction. It is therefore clear that the information treatment program has to be designed for supplying the voltage complement (i.e. in the present case 9 volts instead of 3 volts), or for "complementing" the value which is read as a function of the rotation direction.
Moreover, the power supplied to the electronics by the power source, that is the voltage of the vehicle battery, can vary within large limits, for example according to the temperature or to the charge level which is more or less high. In this respect, it can be admitted that a 12 volt battery supplies in fact a voltage varying between 8 and 20 volts. Thus and by way of example, it is seen that when the slider is half-way along its stroke, the corresponding signal issued from the slider will be of 4.5 volts if the battery supplies 9 volts, whilst the signal will be of 9 volts if the battery supplies 18 volts. Consequently, the value of the signal transmitted to the computer controlling the motor may appear as at random since it does not necessarily refer to the value stored under identical conditions, which means that for a given stored value, the information applied to the motor will be variable, and therefore the setting of the corresponding motor will vary.
The hereabove proposed arrangement consisting in connecting directly in parallel with the setting motor the two potentiometers supplying lines, if it actually reduces efficiently the number of lines and avoids providing for an extra voltage source, seems however unapplicable in fact.
The present invention allows nevertheless to make such an arrangement possible.